Composite-Coated Battery Separator for Adhesion Without Pore Blockage
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Solution Overview
Problem
Secondary batteries face challenges in balancing cycling performance and safety performance, particularly due to excessive adhesion between the separator and electrode plates leading to lithium ion transport blockages and thermal issues during high-temperature conditions.
Innovation Solution
A separator with a coating comprising composite particles of polyacrylate and inorganic particles, where the inorganic particles are arranged between polyacrylate particles, forming bulges that enhance adhesion, compressive modulus, and ionic conductivity, while also forming a film structure to delay thermal spread.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the separator coating uses polyacrylate particles to improve adhesion, then adhesion between separator and electrode plate increases, but compressive modulus decreases causing pore blockage and deteriorated kinetic performance
Solution Approach 1:
The patent uses composite particles comprising polyacrylate particles and inorganic particles (such as aluminum oxide, silicon oxide, or titanium oxide) in a mass ratio of 1:9 to 9:1. This composite structure combines the adhesive properties of polyacrylate with the high compressive modulus of inorganic particles, achieving both strong adhesion and maintained pore structure. The inorganic particles act as structural support while polyacrylate provides bonding, resolving the contradiction between adhesion strength and compressive modulus.
2Strength
If the separator coating uses polyvinylidene fluoride particles, then adhesion is achieved, but resistance increases and ionic conductivity decreases
Solution Approach 1:
The patent changes the material composition parameter of the coating particles from polyvinylidene fluoride to a composite of polyacrylate and inorganic particles. This parameter change fundamentally alters the electrical properties of the coating, reducing resistance and improving ionic conductivity while maintaining adhesion. The inorganic particles in the composite provide pathways for ion transport, resolving the contradiction between adhesion and ionic conductivity.
3Reliability
If the separator coating provides strong adhesion to prevent detachment, then safety improves, but lithium ion transport channels are blocked and kinetic performance deteriorates
Solution Approach 1:
The patent creates local quality differentiation within the coating structure by using composite particles where inorganic particles provide structural rigidity and pore maintenance while polyacrylate particles provide adhesion. The coating thickness and particle size distribution are optimized to ensure that adhesion function is localized at the interface while ion transport channels remain open in the bulk structure, resolving the contradiction between safety and kinetic performance.
4Ease of manufacture
If the separator coating uses existing materials to achieve adhesion, then manufacturing is simplified, but compressive modulus is insufficient and pore collapse occurs under swelling force
Solution Approach 1:
The patent employs composite particles of polyacrylate and inorganic materials that can be directly applied to the separator substrate through conventional coating methods. The composite structure inherently provides high compressive modulus due to the inorganic component, preventing pore collapse under electrode swelling forces while maintaining manufacturing simplicity. The inorganic particles serve as rigid scaffolding that maintains structural integrity under compression.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The separator achieves improved kinetic and safety performance by maintaining appropriate adhesion, preventing lithium ion blockages, and effectively managing thermal runaway through the formation of bulges and enhanced ionic conductivity.
Implementation Method 1
the first inorganic particle is present between at least two of the polyacrylate particles... avoids adhesion of the composite particles during high-temperature granulation
Implementation Method 2
the composite particles form bulges on surface of the coating... implements appropriate adhesion between the separator and the electrode plate
Implementation Method 3
improves ionic conductivity of the separator... reduces resistance of the separator and implements appropriate adhesion
Implementation Method 4
when high temperature is generated due to thermal runaway of the battery, the bulges formed by the composite particles on the surface of the coating can form a widespread film structure to reduce or block the ion transport channels and delay thermal spread
Data Source
AI summary
A separator includes a substrate and a coating. The coating is formed on at least a portion of surface of the substrate. The coating includes composite particles and a binder. The composite particles form bulges on surface of the coating. The composite particles include polyacrylate particles and first inorganic particles. The first inorganic particle is present between at least two of the polyacrylate particles.